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A095306
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Numbers n such that r(k) * 2^n + 1 is prime, where r() = A002275 the repunits and k is the number of decimal digits of 2^n.
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0
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1, 2, 5, 12, 19, 107, 117, 159, 217, 517, 868, 1412, 1636, 4051, 5965, 9128
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OFFSET
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1,2
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COMMENTS
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a(1) through a(16) have been proved to be prime with WinPFGW. a(16) has 5495 digits. No more terms up to 11700.
Results were computed using the PrimeFormGW (PFGW) primality-testing program. - Hugo Pfoertner, Nov 14 2019
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LINKS
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EXAMPLE
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a(5)=19 because 111111 * 2^19 + 1 = 58254163969, a prime.
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CROSSREFS
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KEYWORD
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more,nonn,base
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AUTHOR
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STATUS
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approved
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